Gene Expression

What is gene expression?

The process in which the information encoded in a gene directs the synthesis of a protein; involves transcription and translation.

What occurs during transcription?

Genetic information in DNA is copied into mRNA through initiation, elongation, and termination.

What is messenger RNA (mRNA)?

A type of RNA that serves as a template for protein synthesis, carrying transcribed information from DNA to ribosomes.

Define translation in terms of gene expression.

The process in which the genetic code carried by mRNA is translated to synthesize a specific protein.

What are ribosomes?

Organelles that synthesize proteins by translating mRNA into amino acids.

What is the genetic code?

The instructions within DNA and RNA that cells use to produce proteins.

What is a codon?

A three nucleotide sequence that codes for a specific amino acid or signals the end of protein synthesis.

What is the template strand in transcription?

The strand of DNA that acts as a base for mRNA transcription.

What is the coding strand?

The strand of DNA that does not get read during transcription but matches the synthesized RNA.

Define reading frame.

The way a sequence of nucleotides in mRNA is sectioned into codons, determining the translation of amino acids.

What role does RNA polymerase play in transcription?

It is the enzyme that reads a DNA sequence and transcribes it into RNA.

What is a promoter?

The DNA sequence where RNA polymerase binds to begin transcription.

What are transcription factors?

Specific proteins that regulate transcription by attaching to specific DNA sequences.

What is the transcription initiation complex?

A complex of proteins, including RNA polymerase, that copies a sequence of nucleotides into an RNA transcript.

What is the TATA box?

A portion of a eukaryotic promoter that helps transcription factors and RNA polymerase recognize and bind to the DNA strand.

What is a 5’ cap?

A modified guanine nucleotide added to pre-mRNA that protects it and helps it get exported from the nucleus.

What is a Poly-A tail?

A sequence of 50-250 AAA nucleotides added to pre-mRNA to prevent degradation and assist with export.

What is RNA splicing?

The process by which pre-mRNA becomes mature mRNA by removing non-coding regions and joining coding regions together.

Define introns.

The portions of RNA removed during RNA splicing that do not get translated into amino acids.

Define exons.

The portions of RNA that remain after modification and are sent out to the cytoplasm.

What is a ribozyme?

RNA molecules that can catalyze chemical reactions, functioning like an enzyme.

What is alternative splicing?

Different ways to splice the same gene, creating protein variability by keeping various combinations of exons.

What is transfer RNA (tRNA)?

Small RNA molecules that transport amino acids to the ribosome for protein synthesis.

Define anticodon.

A three nucleotide sequence in a tRNA molecule that matches the complementary codon in mRNA.

What is the wobble position in a codon?

The third nucleotide of a codon that loosely binds, allowing multiple sequences to code for the same amino acid.

What is the function of ribosomal RNA (rRNA)?

Catalyzes protein synthesis in the ribosomes.

What does the small ribosomal subunit do?

Decodes genetic information during protein synthesis by positioning mRNA and tRNA molecules.

What does the large ribosomal subunit do?

Catalyzes the formation of peptide bonds during protein translation.